kernel.git/tools/testing/selftests/vDSO/Makefile, branch linux-6.16.y

selftests: vDSO: vdso_standalone_test_x86: Switch to nolibc

2025-03-03T19:00:13Z

vdso_standalone_test_x86 provides its own ASM syscall wrappers and _start() implementation. The in-tree nolibc library already provides this functionality for multiple architectures. By making use of nolibc, the standalone testcase can be built from the exact same codebase as the non-standalone version. Signed-off-by: Thomas Weißschuh Signed-off-by: Thomas Gleixner Reviewed-by: Vincenzo Frascino Acked-by: Shuah Khan Link: https://lore.kernel.org/all/20250226-parse_vdso-nolibc-v2-16-28e14e031ed8@linutronix.de

selftests: vDSO: parse_vdso: Use UAPI headers instead of libc headers

2025-03-03T19:00:12Z

To allow the usage of parse_vdso.c together with a limited libc like nolibc, use the kernels own elf.h and auxvec.h headers. Signed-off-by: Thomas Weißschuh Signed-off-by: Thomas Gleixner Reviewed-by: Vincenzo Frascino Acked-by: Shuah Khan Link: https://lore.kernel.org/all/20250226-parse_vdso-nolibc-v2-12-28e14e031ed8@linutronix.de

selftests: vDSO: unconditionally build getrandom test

2024-10-08T21:21:36Z

Rather than building on supported archs, build on all archs, and then use the presence of the symbol in the vDSO to either skip the test or move forward with it. Note that this means that this test no longer checks whether the symbol was correctly added to the kernel. But hopefully this will be clear enough to developers and we'll cross our fingers that symbols aren't removed by accident and not caught after this change. Signed-off-by: Jason A. Donenfeld Signed-off-by: Shuah Khan

selftests: vDSO: unconditionally build chacha test

2024-10-08T21:21:29Z

Rather than using symlinks to find the vgetrandom-chacha.S file for each arch, store this in a file that uses the compiler to determine architecture, and then make use of weak symbols to skip the test on architectures that don't provide the code. Signed-off-by: Jason A. Donenfeld Signed-off-by: Shuah Khan

s390/vdso: Wire up getrandom() vdso implementation

2024-09-13T18:57:31Z

Provide the s390 specific vdso getrandom() architecture backend. _vdso_rng_data required data is placed within the _vdso_data vvar page, by using a hardcoded offset larger than vdso_data. As required the chacha20 implementation does not write to the stack. The implementation follows more or less the arm64 implementations and makes use of vector instructions. It has a fallback to the getrandom() system call for machines where the vector facility is not installed. The check if the vector facility is installed, as well as an optimization for machines with the vector-enhancements facility 2, is implemented with alternatives, avoiding runtime checks. Note that __kernel_getrandom() is implemented without the vdso user wrapper which would setup a stack frame for odd cases (aka very old glibc variants) where the caller has not done that. All callers of __kernel_getrandom() are required to setup a stack frame, like the C ABI requires it. The vdso testcases vdso_test_getrandom and vdso_test_chacha pass. Benchmark on a z16: $ ./vdso_test_getrandom bench-single vdso: 25000000 times in 0.493703559 seconds syscall: 25000000 times in 6.584025337 seconds Signed-off-by: Heiko Carstens Reviewed-by: Harald Freudenberger Signed-off-by: Jason A. Donenfeld

powerpc/vdso: Wire up getrandom() vDSO implementation on VDSO32

2024-09-13T15:28:36Z

To be consistent with other VDSO functions, the function is called __kernel_getrandom() __arch_chacha20_blocks_nostack() fonction is implemented basically with 32 bits operations. It performs 4 QUARTERROUND operations in parallele. There are enough registers to avoid using the stack: On input: r3: output bytes r4: 32-byte key input r5: 8-byte counter input/output r6: number of 64-byte blocks to write to output During operation: stack: pointer to counter (r5) and non-volatile registers (r14-131) r0: counter of blocks (initialised with r6) r4: Value '4' after key has been read, used for indexing r5-r12: key r14-r15: block counter r16-r31: chacha state At the end: r0, r6-r12: Zeroised r5, r14-r31: Restored Performance on powerpc 885 (using kernel selftest): ~# ./vdso_test_getrandom bench-single vdso: 25000000 times in 62.938002291 seconds libc: 25000000 times in 535.581916866 seconds syscall: 25000000 times in 531.525042806 seconds Performance on powerpc 8321 (using kernel selftest): ~# ./vdso_test_getrandom bench-single vdso: 25000000 times in 16.899318858 seconds libc: 25000000 times in 131.050596522 seconds syscall: 25000000 times in 129.794790389 seconds This first patch adds support for VDSO32. As selftests cannot easily be generated only for VDSO32, and because the following patch brings support for VDSO64 anyway, this patch opts out all code in __arch_chacha20_blocks_nostack() so that vdso_test_chacha will not fail to compile and will not crash on PPC64/PPC64LE, allthough the selftest itself will fail. Signed-off-by: Christophe Leroy Acked-by: Michael Ellerman Signed-off-by: Jason A. Donenfeld

selftests: vDSO: don't include generated headers for chacha test

2024-09-13T15:28:36Z

It's not correct to use $(top_srcdir) for generated header files, for builds that are done out of tree via O=, and $(objtree) isn't valid in the selftests context. Instead, just obviate the need for these generated header files by defining empty stubs in tools/include, which is the same thing that's done for rwlock.h. Reviewed-by: Adhemerval Zanella Signed-off-by: Jason A. Donenfeld

arm64: vDSO: Wire up getrandom() vDSO implementation

2024-09-13T15:28:36Z

Hook up the generic vDSO implementation to the aarch64 vDSO data page. The _vdso_rng_data required data is placed within the _vdso_data vvar page, by using a offset larger than the vdso_data. The vDSO function requires a ChaCha20 implementation that does not write to the stack, and that can do an entire ChaCha20 permutation. The one provided uses NEON on the permute operation, with a fallback to the syscall for chips that do not support AdvSIMD. This also passes the vdso_test_chacha test along with vdso_test_getrandom. The vdso_test_getrandom bench-single result on Neoverse-N1 shows: vdso: 25000000 times in 0.783884250 seconds libc: 25000000 times in 8.780275399 seconds syscall: 25000000 times in 8.786581518 seconds A small fixup to arch/arm64/include/asm/mman.h was required to avoid pulling kernel code into the vDSO, similar to what's already done in arch/arm64/include/asm/rwonce.h. Signed-off-by: Adhemerval Zanella Reviewed-by: Ard Biesheuvel Acked-by: Will Deacon Signed-off-by: Jason A. Donenfeld

selftests: vDSO: build tests with O2 optimization

2024-09-13T15:28:35Z

Without -O2, the generated code for testing chacha function is awful. GCC even implements rol32() as a function of 20 instructions instead of just using the rotlwi instruction. ~# time ./vdso_test_chacha TAP version 13 1..1 ok 1 chacha: PASS real 0m 37.16s user 0m 36.89s sys 0m 0.26s Several other selftests directory add -O2, and the kernel is also always built with optimisation active. Do the same for vDSO selftests. With this patch the time is reduced by approximately 15%. ~# time ./vdso_test_chacha TAP version 13 1..1 ok 1 chacha: PASS real 0m 32.09s user 0m 31.86s sys 0m 0.22s Signed-off-by: Christophe Leroy Signed-off-by: Jason A. Donenfeld

LoongArch: vDSO: Wire up getrandom() vDSO implementation

2024-09-13T15:28:35Z

Hook up the generic vDSO implementation to the LoongArch vDSO data page by providing the required __arch_chacha20_blocks_nostack, __arch_get_k_vdso_rng_data, and getrandom_syscall implementations. Also wire up the selftests. Signed-off-by: Xi Ruoyao Acked-by: Huacai Chen Signed-off-by: Jason A. Donenfeld